Fintech firm Marquis alerts dozens of US banks and credit unions of a data breach after ransomware attack

**Executive summary:** Marquis, a Texas-based fintech marketing and compliance provider, suffered a ransomware attack on August 14 after threat actors exploited a SonicWall zero-day; the intrusion resulted in a confirmed data breach affecting at least 400,000 people and exposing names, dates of birth, postal addresses, bank account/debit/credit card numbers, and Social Security numbers, with impacts focused on U.S. banks and credit unions and the total affected expected to rise.